Answer this question truthfully
### Question: What are the symptoms of Baker's cyst?
### Response: A large cyst may cause some discomfort or stiffness, but there are often no symptoms. There may be a painless or painful swelling behind the knee.
The cyst may feel like a water-filled balloon. Sometimes, the cyst may break open (rupture), causing pain, swelling, and bruising on the back of the knee and calf muscle.
It is important to know whether pain or swelling is caused by a Baker's cyst or a blood clot. A blood clot (deep vein thrombosis) can also cause pain, swelling, and bruising on the back of the knee and calf. A blood clot may be dangerous and requires immediate medical attention.